Yes you right but better you copy and paste the variables from the script part into new qvw. And for synthetic keys do not worry about that just load the tables and remove it from the load script. And by this you also know what are the synthetic keys are created in the QVW application.
No you have to load the QVW file as binary load into another QVW and do not need to write the script again there. Example check this two files File1.qvw and File2.qvw in File2.qvw i binary load the File1.qvw with one table and in file2.qvw there is one binary load of the File1.qvw. Check file1.qvw for the binary load.
Just to add..here from already posted answer, which might give you more clarity:-
Binary load is the load performs for the QVW file means when any QVW file loads into the another QVW and load all structure from another QVW to another QVW. And at a time only single QVW is loaded as binary file.
For example, our dashboards and reporting apps are typically built in 3 stages... we use a handful of apps to acquire and transform data from various sources and export the raw but "formatted" data in QVDs. In a second stage app, we load the qvds into one data model, perform any additional data transformation on the full set. Then finally, the third and final stage is the "front-end" interface where we load the qvw (called a binary load) into an app where the dashboard, reporting and visualizations are created.
For your clarification since you don't have any syn key in previously loaded QVD, of course you wont get here in new as well. Please let me know if your question is clarified while marking it as answered or shoot your next query.
